MSI mode: message-signalled interrupts and DPC latency
SHORT ANSWER
MSI mode sets MSISupported to 1 under the device's Interrupt Management\MessageSignaledInterruptProperties key, switching a device from legacy line-based interrupts to message-signalled interrupts. It reduces DPC latency, which is the mechanism behind audio crackling and micro-stutter. This is one of a small number of registry tweaks from the old era that still has a real measurable effect.
Exactly what it changes
Read straight from the application source. If a tool will not show you this, it is asking for trust it has not earned.
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Enum\<device instance>\Device Parameters\Interrupt Management\MessageSignaledInterruptProperties
MSISupported = 1
Lets the device raise interrupts by writing a message rather than asserting a shared physical line.
What it does
Legacy interrupts use physical lines that devices can share. When several devices share a line, the OS has to poll each to find out who signalled, which adds latency and can serialise unrelated work.
Message-signalled interrupts let a device write directly to a memory address instead. No sharing, no polling, less time spent at high interrupt priority.
The device instance path is different on every machine, which is why this is fiddly to do by hand.
When it helps
- Lower DPC latency, which is the direct cause of audio crackling accompanied by stutter.
- Most noticeable on systems with many PCIe devices competing for interrupt lines.
- Benefits GPU, NVMe and network adapters, not just the GPU.
When it hurts
- A small number of older devices misbehave with MSI enabled — symptoms range from device instability to failure to resume from sleep.
- It has to be applied per device and re-applied if the device is reinstalled, which is exactly the maintenance problem manual tweaking has.
- Not every device honours the setting even when the key exists.
How to undo it
Set MSISupported back to 0 for the affected device and reboot. Frozen Tweaks stores the previous value per device instance, including the case where the value did not exist at all, so it can restore the true original state rather than guessing at 0.
Verdict
Genuinely worth applying, and one of the few places where a tool is meaningfully safer than doing it by hand — because reverting requires remembering the prior state of every device you touched.
Related guides
Everything else we change is listed too
All 127 optimizations are published in full, with what each one does and which are free. You can apply any of them by hand using pages like this one — the tool exists to do it in one click and put it back after every Windows update.